Knives are often used to cut a line along an edge of a workpiece, and it is known in such circumstances to dispose an outrigger-type cutting guide that extends laterally from the knife. U.S. Pat. No. 5,575,070 to Fiskars (November 1996), for example, teaches a cutting implement having a handle with a forward extending blade and a laterally extending guide. The distance between the guide and the blade can be adjusted with a knob carried on the top of the handle. U.S. Pat. No. 4,744,146 to Schmidt (May 1988) teaches a utility knife having a handle having a retractable blade, and a planar guide extending laterally from handle by a controlled distance. U.S. Pat. No. 4,442,595 to Sharrow et al. (April 1984) teaches a laterally spaced guide that is adapted to receive the blade of a utility knife. U.S. Pat. No. 4,713,885 to Keklak et al. (December 1987) teaches a utility knife with a blade guide that descends from the handle.
Each of the cited prior art documents provides a mechanism for controlling the path of a cut of the blade parallel to a side edge of an object being cut. Sometimes the guide is disposed to the left of the blade (as viewed from the user's perspective), and sometimes the guide is disposed to the right of the blade. But in each case there is only one guide, and that guide operates to distance blade only from a right edge or only from a left edge. That limitation reduces the utility of the knife with respect to specific applications that require the opposite orientation.
What is needed is a knife having both a right edge guide and a left edge guide.